This is a 6x4E Thin Composite propeller from Advanced Precision Composites.
For use on Electric powered aircraft only (not for glow engines).
Gray composite propeller blades that assemble onto a propeller hub.
Comes with two adapter rings that adapt to different motor shafts.
Comes in a bag attached to a header card.
One composite propeller
Two composite adapter rings
One instruction sheet
Assembly onto motor or gear drive unit in your Electric plane.
Hub inner diameter: 0.25"